Tracking pixel HTML for open rate on non-Marketo emails
We have a holiday card email that will be sent by individuals (not Marketo) and want to see if there is a way to use Marketo/munchkin to track the open rate of emails that users send by forwarding the holiday card email. Is there a email campaign specific tracking pixel and how would I even set up the tracking in Marketo? I'm not a developer at all and only know very basic HTML so any help is greatly appreciated!